Roughly 75% of all aluminum ever produced is still in use today. This is not only because the metal is highly recyclable, but it’s also a testament to aluminum’s ability to withstand corrosion. Aluminum is the most recyclable material used in multiple industries. It holds its value and is a vital part of most supply chain logistics. Aluminum is a part of our everyday lives, from our soda cans to our cars and buildings we can’t go a day without coming into contact with or utilizing something that is made from Aluminum.
But what is the reason why aluminum is so resistant to corrosion and rust? Let’s take a look.
What is Corrosion?
Corrosion is usually defined as the degradation of metals due to an electrochemical process. The formation of rust on iron, tarnish on silver, and the blue-green patina that develops on copper are all examples of corrosion.
The most common kinds of corrosion result from electrochemical reactions. General corrosion occurs when most or all of the atoms on the same metal surface are oxidized, damaging the entire surface. Most metals are easily oxidized: they tend to lose electrons to oxygen (and other substances) in the air or in water. As oxygen is reduced (gains electrons), it forms an oxide with the metal.
Corrosion is a dangerous and extremely costly problem. Because of it, buildings and bridges can collapse, oil pipelines break, chemical plants leak, and bathrooms flood. Corroded electrical contacts can cause fires and other problems, corroded medical implants may lead to blood poisoning, and air pollution has caused corrosion damage to works of art around the world. Corrosion threatens the safe disposal of radioactive waste that must be stored in containers for tens of thousands of years.
Can Aluminum Rust?
Rusting is a form of corrosion that’s specific to iron and steel (because it contains iron). In fact, rust is the common name for iron oxide, when iron or steel bonds with oxygen and undergoes oxidation. Therefore, aluminum can’t rust.
What is the timeframe for Aluminum Oxidation?
Aluminum oxidation happens at a faster rate than steel oxidation because aluminum has a stronger “liking” for oxygen. When all the aluminum atoms have bonded with oxygen, the oxidation process stops.
How Can You Identify Aluminum Corrosion?
Unlike iron that flakes through when it corrodes, aluminum oxide forms a hard, white-tinted surface skin. Aluminum corrosion is known as aluminum oxide, a very hard material that actually protects the aluminum from further corrosion. Aluminum oxide corrosion also looks a lot more like aluminum (dull gray to powdery white in color), so it isn’t as easy to notice as rusted iron.
How to Treat Bare Aluminum
That aluminum oxidation can protect bare aluminum indefinitely, but if you want to paint the aluminum you’ll need to sand off the aluminum oxide coating and get to clean aluminum. This is because most commercial coatings don’t adhere well to aluminum oxide. Your paint job won’t last long on any aluminum surface if you haven’t sanded and cleaned it thoroughly prior to painting. Make sure to find a metal primer specifically designed for aluminum surfaces as well, since most basic primers and paints are not designed for this application.
How Do You Stop Aluminum Corrosion?
Since aluminum so readily bonds with oxygen, there’s little that can be done about aluminum oxidation. Aluminum corrosion, however, can be a serious problem. To prevent aluminum corrosion, you should consider:
- First and foremost, choosing the correct alloy: some alloys have better corrosion-resistance than others.
- Applying a protective coating
- Minimizing the effect of galvanic corrosion. Galvanic corrosion is caused by putting two dissimilar metals, like aluminum and steel, next to each other.
- Paint – provides a moisture-proof barrier
- Powder coat
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